1. Technical Field
Embodiments of the present disclosure relate to semiconductor devices, and more particularly to a semiconductor device configured to generate a refresh pulse for executing a refresh operation.
2. Related Art
Dynamic random access random (DRAM) devices of semiconductor devices may lose their stored data as time elapses even though their power supply voltages are supplied, unlike static random access random (SRAM) devices and flash memory devices. This may be due to leakage currents of cell capacitors constituting memory cells of the DRAM devices together with cell transistors. Thus, the cell capacitors of the DRAM devices have to be periodically recharged to retain or refresh their stored data. This operation may be referred to as a refresh operation. The refresh operation may be performed by activating a word line at least once within a data retention time of the memory cells to amplify the data stored in the memory cells. The data retention time may correspond to a maximum time that the cell capacitors can retain minimum charges which are required to reveal correct logic data without any refresh operations.
The refresh operation may be categorized as either an auto-refresh operation or a self-refresh operation. The auto-refresh operation may be executed by refresh commands outputted from a controller that controls the DRAM devices, and the self-refresh operation may be executed by counters included in the DRAM devices in a power down mode.
Meanwhile, it may be necessary to control operation conditions of circuit blocks in a semiconductor device according to a variation of internal temperature of the semiconductor device. Temperature sensors such as digital temperature sensor regulators (DTSRs), analog temperature sensor regulators (ATSRs) or digital temperature compensated self-refresh (DTCSRs) have been widely used to control the operation conditions of semiconductor devices such as DRAM devices according to a variation of the internal temperature of the semiconductor devices.